In this post, KrazyDad Super-Tough v.5, b.6, #5 survives a wrap of one coloring cluster, only to fall to a second.
The bypass starts with two 3-fills, one resolved. Then in line marking, there’s an outbreak of naked pairs.
Here is the hard won line marked grid.
Would you go with the Super Tough experience and start a coloring cluster?
Where?
How about on the C box diagonal and column 4?
Going on to the bv map, there’s a tight little XY ANL.
It’s not a little spur in an XY railway, it’s the only XY chain in town, and a simple one at that. Agree?
Moving on to the XYZ map, we get one of those unworkable rectangular XYZ-wings. But wait, it is workable. 3r9c9 sees two of the three toxic set 3’s You could dispense with the forcing chain. If you see blue 3r9c6, you see blue 3r5c5. You don’t even need 3r9c6. Seeing 3r4c1 does the same thing. It’s an ER, or a 3-chain, or a shortcut i583-wing.
Not to be outdone, two X-panels step in with X-chain ANL. The 2-chain gets a bv partner for a clue, but the 3-chain tops that by wrapping blue.
Surprisingly, KDST 565 hangs on after (W2, W9, green), and a second cluster traps two, wrapping red, and triggering a quick collapse.
Surprisingly, KDST 565 hangs on after (W2, W9, green), and a second cluster traps two, wrapping red, and triggering a quick collapse.
Systematic Sudoku 